1. Field of the Invention
The present invention relates to an image forming apparatus having a charge member disposed near an image bearing member.
2. Description of the Related Art
Conventionally, as an image forming apparatus such as a copying machine and a laser beam printer, there has been known an image forming apparatus employing an intermediate transfer system with an intermediate transfer member. In the image forming apparatus employing the intermediate transfer system, first, as a primary transfer process, a toner image, which is a transferable image formed on a surface of a photosensitive member serving as a first image bearing member, is transferred onto an intermediate transfer member serving as a second image bearing member. The primary transfer process is repeatedly executed for each of multiple color toner images, to thereby form multiple color toner images on a surface of the intermediate transfer member. After that, as a secondary transfer process, the multiple color toner images formed on the surface of the intermediate transfer member are collectively transferred onto a surface of a transfer material such as paper. Then, the multiple color toner images collectively transferred onto the transfer material are fused and mixed to be fixed onto the transfer material by a fixing unit. As a result, for example, a full-color image as a recorded image is formed on the transfer material.
As a method of collecting a toner (secondary transfer residual toner) remaining on the intermediate transfer member after the secondary transfer process, there is known a method of charging the residual toner to a polarity opposite to a normal charging polarity by a charge member and transferring the residual toner back to the photosensitive member during the primary transfer process, to thereby collect the residual toner (see Japanese Patent Application Laid-Open No. 2005-284186).
While the charge member disclosed in Japanese Patent Application Laid-Open No. 2005-284186 is a roller, a charge brush is used as the charge member in the present invention in order to improve a charging ability of the charge member. The charge brush is advantageous in that a diffusion effect by the brush is expected in a case of charging a toner, and in that a charging efficiency of the toner is improved.
Meanwhile, the charge brush has a brush shape, so the charge brush is liable to store (hold) toner as compared with the roller. When an amount of the toner to be held is large, a large amount of toner is removed from the charge brush when a voltage applied to the charge brush is switched or turned off. In a case where a subsequent toner image is superimposed on the toner, which is removed from the charge brush, to be formed on the intermediate transfer member, there arises a problem in that the quality of the subsequent toner image is deteriorated.